All-optical XOR operation has been demonstrated using a semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) and delayed interferometer (DI) at 80 Gb/s. The DI is based on a polarization maintaining loop mirror (PML). The results show using the PML-DI to perform differential scheme can improve the pulse quality of the XOR result.
All optical XOR, AND, OR, and, NOR functionality has been demonstrated experimentally using
semiconductor optical amplifier (SOA) based devices at 40 Gb/s, 80 Gb/s. The performance of
the optical logic operations has been analyzed by solving the rate equation of the SOA
numerically. The high-speed operation is limited by the gain and phase recovery times in the
SOA. In order to solve these limitations, a differential scheme for XOR operation has been
experimentally investigated. This scheme is potentially capable of XOR operation to > 100 Gb/s.
In this paper, detailed analyses of the conversion efficiency in high-speed clock recovery based on Mach-Zehnder (MZ) modulator has been carried out. The theoretical results show the conversion efficiency changes with RF driving power and the mixing order. For high order clock recovery, the cascaded MZ modulator provides higher conversion efficiency. A study of clock recovery at 160 Gb/s using the cascaded MZ modulator has been carried out. The experimental results agree with the results of the analysis.
The performances of all-optical logic gates AND, OR, XOR, NOT based on quantum dot semiconductor optical amplifier (QD SOA) devices have been simulated. The saturation power, optical gain and optical
phase response of a QD SOA has been analyzed numerically using a rate equation model of quantum dots embedded in a wetting layer. The calculated response is used to model the performance of the logic gates. Impacts of injection current and the input signal power on system quality factor have been studied. For the parameters used in this paper, all-optical logic gates using QD-SOA is capable of operating at speeds of ~ 250Gb/s.
In this work, an optical short pulse generator is designed consisting of a pulse compressor and cascaded notch filter type repetition rate doublers. The performance characteristics such as pulse width and peak power as a function of design parameters are studied. The pulse compressor is optimized based on the simulation results. The 6ps wide pulses at 20 GHz repetition rate directly generated from mode-locked fiber laser (MLL) are compressed to 1.25ps wide pulses. Using a set of polarization maintaining fiber (PMF) loop mirrors the repetition rate is quadrupled and stable 1.45 ps wide pulse train at 80GHz is achieved.
In this work, we demonstrate clock recovery from a patterned 160Gb/s optical-time-division-multiplexed (OTDM) return-to-zero (RZ) data stream. A cascaded LiNbO3 Mach-Zehnder modulator is employed as an efficient optical-electrical mixer. A phase-locked-loop (PLL) is used to lock the cross-correlation component between the optical signal and a local oscillating signal. As a result, clock signal at 10GHz is extracted from the 160Gb/s optical TDM signal. The measured root-mean-square (RMS) timing jitter of the 10GHz clock signal is ~ 130fs.
All optical XOR, AND, and, OR functionality has been demonstrated experimentally using semiconductor optical amplifier (SOA) based devices at 40 Gb/s, 80 Gb/s. The performance of the optical logic operations has been analyzed by solving the rate equation of the SOA numerically. The high-speed operation is limited by the gain and phase recovery times in the SOA. In order to solve these limitations, a differential scheme for XOR operation has been experimentally investigated. This scheme is potentially capable of XOR operation to > 100 Gb/s.
In this paper, we demonstrate clock recovery from a patterned 160Gb/s optical-time-division-multiplexed (OTDM) return-to-zero (RZ) data stream. A cascaded LiNbO3 Mach-Zehnder modulator is employed as an efficient optical-electrical mixer. A phase-locked-loop (PLL) is used to lock the cross-correlation component between the optical signal and a local oscillating signal. As a result, clock signal at 10GHz is extracted from the 160Gb/s optical TDM signal. The measured root-mean-square (RMS) timing jitter of the 10GHz clock signal is ~ 130fs.
All-optical OR operation has been demonstrated using a semiconductor optical amplifier (SOA) and delayed interferometer (DI) at 20 Gb/s and 40 Gb/s. The DI is based on a polarization maintaining loop mirror. Q-factor of the operation is discussed through the numerical simulations. The results show the OR gate operation rate is limited by the carrier lifetime and the input pulse energy.
In this paper, we demonstrate a technique for suppressing the intensity noise of the erbium doped fiber lasers. We show that by introducing negative feedback into the system through the use of a self-biased intracavity loss modulator, the relaxation oscillation noise of the fiber laser could be suppressed by as much as 20 dB. To explain the observed noise reduction phenomenon, a simple theory based on teh linearized rate equation has been developed and also been supported by experimental measurements. We also derive a formula for estimating the maximum achievalbe intesity noise suppression ratio.
We present two methods for timing jitter measurement. The first method uses the spectral content of the noise, and, the second method uses autocorrelation and cross correlation of the pulsed output. For a distributed feedback (DFB) laser gain switched at 1 GHz, the timing jitter is about 3-4 ps. When an external CW laser injected into the DFB laser, the timing jitter can be reduced to 1-1.5 ps.
We demonstrate simultaneous stabilized operation of a mode locked ring fiber laser at two wavelengths. At one of the wavelengths the mode locked operation is at 10 GHz and it is at 40 GHz at the second wavelength. The laser has an intracavity LiNbO3 modulator driven at 10 GHz. The 40 GHz pulses are obtained by rational harmonic mode locking. Pulses with widths in 5 to 8 ps range are obtained.
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